Anticoagulants of blood are divided into those of direct and indirect action. While there is a great variety of indirect-action anticoagulants, synthetic anticoagulants of direct action are practically non-existent,
Direct-action anticoagulants prevent thrombogenesis, for which reason they are of great help in treating cases of myocardial infarction, pulmonary embolism and other diseases leading to acute thrombosis.
The significance of producing new direct-action anticoagulants of blood is apparent in view of the current spread of cardiovacular disorders.
Today, the commonest direct-action anticoagulant of blood is heparin which is an ester of sulfurinc acid and mucopolysaccharide. This natural product is prepared from lung tissues of bovine animals. Heparin is quite expensive, although its effect wears off in four or five hours. The known synthetic direct-action anticoagulants include sulfonated hydrolyzate of pectin according to Swiss Pat. No. 342,556 of Jan. 15, 1970; sulfonated starch (cf. Sigiura Mamoru, Sigiura Shoji, Yamamoto Hajime, Polia Pharmacol. Jap., 69, No 5, pp. 689-693, 1973); sulfonated chitosan (cf. I. G. Kochnev, V. M. Molodkin et al., Zhurnal Polevoy Khirurghii/Journal of Field Surgery, 46, Series 6, pp. 1141-1142, 1973); derivatives of cis-1,4-polyisoprene containing aminosulfonate and carboxylic groups (cf. T. Beudeling, L. Van der Does, A. Bantjes, W. L. Sederel, J. Biomed. Mat. Res, 8, Nos 1, 2, p. 375, 1974); sulfonated polyvinylalcohol (cf. V. I. Shumakov, Experimentalnaya Khirurghiya (Experimental Surgery), No 1, 26, 1971); sodium polyethylene sulfonate (cf. M. Bruster, Klin. Wochenscher, 44, No 13, p. 766, 1966).
All the above compounds have proved to be unapplicable because of their toxicity and low anticoagulant effect.
There is further known a synthetic direct-action anticoagulant of blood prepared by sulfonating cellulose (cf. M. M. Kovaloyv, V. K. Tyoply, V. D. Yankovsky, N. A. Ivanova, A. F. Rekasheva, "Synantrine", Naukova Dumka Publishers, Kiev, 1974). The latter compound, too, is relatively toxic and features a short-lived effect.